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Name ___________________________ Chapter 13 Class ___________________ Date _____________ Earth’s History Section 13.1 Precambrian Time: Vast and Puzzling This section discusses Earth’s history during the Precambrian time. Reading Strategy Building Vocabulary As you read this section, use the information about the vocabulary terms to complete these phrases. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. 1. Shields are composed of a. of b. ; are evidence ; and are significant to Precambrian time because c. . 2. Stromatolites are composed of d. are evidence of e. ; ; and are significant to Precambrian time because f. . Precambrian History The Precambrian time starts at continues until the start of the over 4 billion years later. and period 2. Circle the approximate percentage of the geologic time scale that Precambrian time comprises. a. 44 percent b. 50 percent c. 73 percent d. 88 percent 3. Explain why Precambrian history is scattered and incomplete. Earth Science Guided Reading and Study Workbook ■ 96 © Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved. 1. Name ___________________________ Chapter 13 Class ___________________ Earth’s History Match each description to its term. Description Term the most common Precambrian fossils 5. large core areas of Precambrian rocks dominating the surface of some continents 6. source of information about Precambrian rocks 7. a hard, dense chemical sedimentary rock Complete the following flowchart. 4. 8. Date _____________ a. shields b. stromatolites c. ores d. chert How Earth’s Atmosphere Changed Over Time High-velocity impacts of nuclear debris As the planet cools, caused gases dissolved in the molten rock to be released into the atmosphere. Earth’s original atmosphere was made up of water vapor, carbon dioxide, nitrogen, and © Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved. several trace gases, but no oxygen. Primitive plants The Precambrian rock record suggests 9. Circle the letter of each sentence that is true about Precambrian fossils. a. The most common Precambrian fossils are stromatolites. b. Many of the ancient fossils are preserved in chert. c. Most fossils found in chert are eukaryotes. d. Animal fossils date to the early Precambrian time. 10. Is the following sentence true or false? Trace fossils are not fossils of the animals themselves but are impressions of their activities, such as trails and worm holes. Earth Science Guided Reading and Study Workbook ■ 97